1. Field of the Invention
The present invention relates to a torsional vibration damper having a primary element with at least one primary driver, having a secondary element with at least one secondary driver, having at least one spring device between the primary driver and the secondary driver for the resiliently elastic coupling of the primary element and secondary element, and having at least one end block which is arranged on the end side of the spring device, with the primary element being rotatable relative to the secondary element from a neutral position into a first position, in which the primary driver is supported only on the spring device, and from the first position onward into a second position, in which the primary driver is supported on the spring device and on the end block. The present invention also relates to a drive train having a torsional vibration damper of said type.
2. Description of the Related Art
The prior art discloses various torsional vibration dampers which are also referred to as rotary vibration dampers or dual-mass flywheels. The known torsional vibration dampers are used in particular in automobile manufacture for elastically coupling the internal combustion engine and the drive train. In this way, it is intended to prevent torsional vibrations from being transmitted from the internal combustion engine to the drive train or to the transmission. Such a transmission occurs in particular in the case of internal combustion engines with a comparatively small number of cylinders and at low engine speeds. With effective damping of such vibrations, the internal combustion engine can be operated at low rotational speeds, which generally results in reduced fuel consumption.
For example, DE 199 58 814 A1 describes a rotary vibration damper in the form of a dual-mass flywheel. The known rotary vibration damper has a central disk element with a plurality of support arms arranged on the periphery, and a further disk element which is composed of two covering disk elements on which support projections are provided. Spring devices for resiliently elastically coupling the central disk element and the further disk element are provided between the support projections. The spring devices are composed of a plurality of spring elements which are arranged in succession in the tangential direction.
Support elements are arranged on the end sides of the spring devices known from DE 199 58 814 A1, which support elements are in practice also referred to as end blocks and adjoin an end-side spring element of the respective spring device. The end block also has a leadthrough opening which faces toward the support arm, while the support arm comprises a projection which faces toward the leadthrough opening. If the central disk element is rotated from a neutral position into a first position relative to the further disk element, then the projection of the support arm extends through the passage opening and is supported on the end-side spring element even before the support arm is supported on the end block. If the central disk element is rotated beyond the first position into a second position, then the spring element is already acted on directly with pressure by the projection. When the second position is reached, the support arm is also supported on the end block, such that the spring element is additionally acted on with pressure via the end block.
The known rotary vibration damper, by means of its spring device in which the spring element is acted on with pressure firstly directly by the support arm and subsequently indirectly via the end block, ensures that the damping function has a smooth onset. It is also possible for the transition noises in the event of a change from traction to overrun, which transition noises are generated as the support arm impacts against the end block, to be reduced in this way. A disadvantage is however that the initial damping effect is not sufficiently intense if the support arm is acted on with a particularly large torque. In said case, when the support arm impacts against the end block, transition noises still occur. Furthermore, severe wear or abrasion occurs on the end block, which wear or abrasion leads inter cilia to a contamination of the oil within the torsional vibration damper.
To prevent the abovementioned transition noises during changes from traction to overrun, EP 1584839 A1 proposes a torsional vibration damper in which the end block is designed such that the torque is transmitted exclusively directly from a primary driver or support arm to the spring element of the spring device. The primary driver is no longer supported at all on the end block. In this way, although the transition noises are reliably reduced, problems can occur here with regard to the guidance of the end block in the tangential direction.
It is therefore an object of the present invention to create a torsional vibration damper which firstly ensures low transition noises in the event of changes from traction to overrun and low wear or abrasion to the end block, and secondly ensures reliable guidance and functioning of the end block. The invention is also based on the object of creating a drive train having a torsional vibration damper of said type.